The FARC has already handed over the coordinates of the release location, according to leftist senator Piedad Cordoba.
Both the Colombian government and the Red Cross have signed the protocol for the operation, and the Brazilian air force will help with logistics.
Both men are Colombian soldiers. Moncayo has been held by the FARC since 1997, while Calvo has been held since April 2009.
The FARC is reportedly holding 24 police officers and soldiers captive.